An Unexplored Realm in the Heartland of the Southern Gulf ... - Famsi

Laboratory Procedures
A total of 177 specimens were used in the weak acid-extraction ICP–OES
analysis, 87 from Plaza I (Figure 4.26) and 90 from Plaza II (Figure 4.27). The location
of these specimens is identified by a red diamond on the grid maps. Each sample was
prepared for analysis by James Hawkin and Claire Novotny of the University of South
Florida, Department of Anthropology, under the direction of Dr. E. Christian Wells. Each
sample was homogenized through thorough mixing, and a 2.0 g sample was weighed out.
The fine consistency of the soil precluded the need for sieving or pulverizing. The sample
was mixed in a polyethylene vial with 20 mL of extract composed of 50 mL HC1, 10 mL
HNO3, and diluted with 1000 mL of Type II deionized H2O (0.60 M HC1 + 0.16 M
HNO3). Sample mixtures were highly agitated for 30 minutes on an electric platform
shaker at 200 rpm. The solution was then filtered through ashless filter paper and
decanted into a clean polyethylene vial. The mild acid extraction method was used
because recent studies have demonstrated this procedure illustrates the anthropogenic
components in the soils (Burton and Simpson 1993; Middleton and Price 1996).
The prepared samples were sent to the Paleoclimatology, Paleoceanography and
Biogeochemistry Laboratory at the University of South Florida’s College of Marine
Science on the St. Petersburg Campus. There the samples were analyzed using a Perkin-
Elmer 4300-DV ICP-OES (Dual View Inductively Coupled Plasma-Optical Emission
Spectrometer) equipped with a cyclonic spray chamber and Meinhard C3 High-Solids
nebulizer. The equipment was calibrated using known solution standards for elements of
interest.
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